“After a 32-year battle with Parkinson’s disease, Muhammad Ali has passed away at the age of 74,” family spokesman Bob Gunell said.

“The three-time World Heavyweight Champion boxer died this evening. Muhammad Ali’s funeral will take place in his hometown of Louisville, Kentucky. The Ali family would like to thank everyone for their thoughts, prayers and support and asks for privacy at this time.”

He had been suffering from a respiratory illness, a condition that was complicated by Parkinson’s disease.

Ali’s funeral will take place in his hometown of Louisville, Kentucky, said his family.

Ali fought for and won the heavyweight title a record-setting three times in his 22-year career, and his rivalries with Sonny Liston, George Foreman and, especially, Joe Frazier are the stuff of boxing legend.

Charismatic, proud, and quotable, Ali’s trash-talking, self-aggrandizing and often rhyming interviews made him a new kind of sports celebrity, and his commitment to acting upon his personal convictions redefined the role of professional athlete as public figure.

His conversion to Islam in 1963 alienated white boxing fans, and after he refused to serve in the Vietnam War, he was prevented from boxing for four years at the height of his career.

People who never watched a boxing match in their lives, or who never learned to speak a word of English, knew who Muhammad Ali was, and knew he was, as he himself said, “the greatest.”

Tributes for the heavyweight great have been pouring in from across the world.

“Muhammad Ali shook up the world. And the world is better for it,” said US President Barack Obama and his wife Michelle.

Former President Bill Clinton – husband of Democratic frontrunner Hillary – said the boxer had been “courageous in the ring, inspiring to the young, compassionate to those in need, and strong and good-humoured in bearing the burden of his own health challenges”.

George Foreman, who lost his world title to Ali in the famous “Rumble in the Jungle” fight in Kinshasa in 1974, called him one of the greatest human beings he had ever met.

American civil rights campaigner Jesse Jackson said Ali had been willing to sacrifice the crown and money for his principles when he refused to serve in the Vietnam war.

Ali was born Cassius Marcellus Clay Jr. on January 17th, 1942, in Louisville, Kentucky. His father, Cassius, painted billboards and signs; his mother, Odessa, was a household domestic. When Clay was 12, his bicycle was stolen, and a police officer (who also happened to be a boxing coach) overheard the angry boy threatening harm if he ever found the thief and told him he’d better learn to box first.

Clay took his advice. As an amateur, his record was 100-5. He won six state Golden Gloves titles and two national titles, then went to the 1960 Summer Olympics in Rome, where he won the Light Heavyweight gold medal. Returning from Rome, Clay went pro in October 1960.

Nicknamed “The Greatest”, the American beat Sonny Liston in 1964 to win his first world title and became the first boxer to capture a world heavyweight title on three separate occasions.

Around this time he hired Angelo Dundee, the man who would be his trainer until the boxer retired in 1981, having won 56 of his 61 fights.

Crowned “Sportsman of the Century” by Sports Illustrated and “Sports Personality of the Century” by the BBC, Ali was noted for his pre- and post-fight talk and bold fight predictions just as much as his boxing skills inside the ring.

But he was also a civil rights campaigner and poet who transcended the bounds of sport, race and nationality.

Asked how he would like to be remembered, he once said:

“As a man who never sold out his people. But if that’s too much, then just a good boxer.

“I won’t even mind if you don’t mention how pretty I was.”

Despite his illness, however, Ali remained active for many years. He was now a celebrated public figure, honored by the establishment that once loathed him.

He rode in the 1987 Tournament of Roses Parade as part of the U.S. Constitution’s 200th birthday celebration and lit the flame at the 1996 Summer Olympics in Atlanta.

A 2001 film directed by Michael Mann, titled Ali, starred Will Smith in the lead role and garnered critical acclaim.

Ali persisted as a social activist as well. He travelled to Iraq in 1991, attempting to negotiate the release of U.S. hostages with Saddam Hussein, and to Afghanistan in 2012 as a United Nations Messenger of Peace.

Ali is survived by his fourth wife, Lonnie, who he married in 1986, and nine children: seven daughters and two sons. His youngest daughter, Laila, born in 1977, became a professional boxer, and retired undefeated in 2007.

“It’s a sad day for life, man. I loved Muhammad Ali, he was my friend. Ali will never die,” Don King, who promoted some of Ali’s biggest fights, told The Associated Press. “Like Martin Luther King his spirit will live on, he stood for the world.”